ABSTRACT
[Objective]To evaluate the incidence and predictors of stiff knees after primary TKA.[Method]A retrospective review was given to the data from 1216 patients undergoing primary total knee arthroplasty between October 1996 and October 2006.Forty-five stiff TKA patients with a 1-year postoperative flexion range of less than 90?was taken as treatment group.Forty-five TKA patients with greater than 90? flexion at 1 year postoperative as control group.The age,sex,body mass index,American Society of Anesthesiologists(ASA) rating,surgeon,implant type,and fixation of the control group were matched to those of the treatment group.A case-control study was conducted to determine predictive factors of stiff TKA.[Result]No significant differences were found with regard to the mean age,ratio of sex and preoperative medical comorbidities.Preoperative flexion and intraoperative flexion were predictive of ultimate postoperative flexion(P=0.001 and P=0.039,respectively).Preoperative and postoperative relatively decreased patellar heightwere significantly correlated with postoperative stiffness(P=0.001).[Conclusion]Stiffness post-TKA is multifactorial,careful attention to surgical exposure,restoring gap kinematics,minimizing surgical trauma to the patellar ligament/extensor mechanism,appropriate implant selection,and physiotherapy may all serve to reduce the incidence of post-TKA stiffness.